1. Field of the Invention
The present invention relates generally to location based services, and in particular, to a method, apparatus, and article of manufacture for refining the location of a mobile device.
2. Description of the Related Art
Detecting the location of a mobile device (e.g., a cellular phone, a personal digital assistant [PDA], etc.) is fundamental to providing location based services (LBS). Location based services are applications/services that utilize or are based on the location of a device. For example, detecting that a device is located on a particular street (e.g., McInnis Parkway) allows an LBS application to provide a nearby theatre (e.g., Northgate Mall Cinema) when a user requests the closest entertainment option. Additional examples of LBS applications include traffic updates, location sensitive billing, fleet management, and asset and people tracking. However, the device location currently provided by prior art wireless carriers is coarse (e.g., with precision ranging in 100s of meters or even 1000 meters or more). LBS services therefore need to refine this location to make the services valuable. These problems may be better understood by describing prior art location detection.
Location Detection Prior Art
A wide variety of methods/protocols are used by mobile device carriers to determine and provide a device's location to an LBS application. For example, different methods may be used to identify the device. Further, different protocols may be used to communicate with the carrier's mobile positioning server (MPS). Different formats for request/response exchange with the mobile positioning server may also be used. Additionally, there may be different levels of robustness, error handling, and network infrastructure stability.
There is often differing levels of precision/accuracy in the location provided by the MPS. For example, most location technology is cell sector based (i.e., a location is merely identified as being within a particular cell sector). Accordingly, the approximate location provided by the MPS could be 150 meters to several 100 meters, or even 1000 meters or more from the actual location of the device. Thus, most MPS services only provide a geographic region that a mobile device is within that is highly inaccurate.
Such imprecision affects the value of an LBS application to a user. For example, more popular LBS applications such as business/entertainment finders, friend finders, and/or routing could be significantly more valuable to the user, if the approximate current location is more accurate. Accordingly, what is needed is the capability to refine an approximate location to a location that better represents the user's true location or to a prominent landmark in the vicinity of the user that the user can readily identify.
FIG. 1 illustrates an approximate location and an error polygon representing imprecision in the location. A device's approximate location is indicated as circle 100. An error polygon 102 represents the imprecision in the location. The problem in the prior art is to produce a refined location 104 that likely represents the user's true position. In addition, refinement is expected to produce a location 104 that is in the vicinity of the user's current location and is prominent enough to be readily identified by the user. Further, in the best case, this refined location 104 equates to the user's true current position.